Multi-fire and variable fire diverter conveyor system and method

ABSTRACT

A conveyor system ( 10 ) for transporting items in a first direction and diverting the items to the appropriate ones of a plurality of stations ( 50, 52 ) spaced from one another in the first direction. The system includes at least one diverter region (DR) and a diverter ( 16 ) arranged in each diverter region. Each diverter diverts items transported by the conveyor to the appropriate ones of the stations in response to corresponding fire signals. The conveyor system further includes a source of destination information ( 46 ) identifying the stations to which the items transported by the conveyor are to be diverted. The conveyor system also includes a controller system ( 40 ) connected to each diverter and the source for generating, and providing to each diverter, the fire signal for each item transported by the conveyor based on destination information from the source regarding to which one of the stations the item is to be diverted.

PRIOR APPLICATION INFORMATION

This is a divisional application of U.S. Pat. application Ser. No.09/347,765, filed Jul. 6, 1999, now U.S. Pat. No. 6,359,247.

FIELD OF THE INVENTION

The present invention relates to conveyor systems and conveying methodsand, in particular, to such systems and methods having a multi-fire modeof operation involving multiple diversion points on a single diverter,and a variable fire mode of operation involving a variable diversionpoint on a single diverter.

BACKGROUND OF THE INVENTION

Conveyor sorting systems and methods for sorting items (e.g., packages)are common in the prior art. Conventional sorting is accomplished byproviding a reader to read a preprinted code on an item to be sortedthat has been placed onto the conveyor system, and thereafter activatingan appropriate diverter in the proximity of the reader to cause the itemto be diverted film the conveyor to an adjacent station. An exemplaryprior art sorting system is described in U.S. Pat. No. 4,249,661 (the'661 patent). Other examples of high-speed sorting apparatus aredisclosed in U.S. Pat. No. 6,085,892 (the '892 patent) and U.S. Pat. No.5,984,498 (the '498 patent), which patents are hereby incorporated byreference.

It is often desirable to sort items traveling on a conveyor intodifferent bins, stackers, conveyors or other devices, referred togenerically herein as “stations,” off to the side of the conveyer,depending on the nature of the item. Presently, this type of sorting isaccomplished using a separate diverter for each station, such asillustrated in FIG. 3 of the '661 patent. However, the need for multiplediverters for such sorting increases the complexity and expense of theconveyer system.

It is also often desirable to sort items of various size based on theirposition relative to the diverter. For example, for relatively longitems it is often desirable to divert the item from the conveyor whenits center in the long dimension reaches a mid-point of the diverter.Similarly, for relatively short items it is often preferable to activate(“fire”) the diverter when a different portion of the package (e.g., itsleading edge) reaches the beginning of the diverter.

As described in U.S. Pat. Nos. 3,242,342, 3,515,254 and 3,512,624, it isknown to divert packages from a conveyor when the center of the packagereaches the mid-point of the diverter. It is also known to take variousactions in a conveyor system as a function of the length of a packagebeing conveyed. See U.S. Pat. No. 3,680,692. Unfortunately, it isbelieved no conveyor systems exist that determine the length of apackage and then fire a diverter when a selected position on the packagereaches a selected position on the diverter as a function of the lengthof the package. As such, known conveyor systems are not particularlywell adapted to conveying packages of widely varying lengths, with theresult that packages are often mis-diverted, turned in an undesirableorientation or not diverted at all.

SUMMARY OF THE INVENTION

The present invention relates to conveyor systems and methods, and inparticular such systems and methods having a multi-fire operationinvolving multiple diversion points on a single diverter, and a combinedmulti-fire and variable fire operation involving a variable diversionpoint on one of multiple diversion points of a diverter. The inventionalso relates to a modular conveyor system.

A first aspect of the invention is a diverter system for diverting itemsto one of a plurality of stations on either side of a conveyor. Thediverter system is designed for use with a conveyor for transportingitems in a first direction. The conveyor includes at least one diverterregion in which the diverter system is positionable. The diverter systemcomprises a diverter for diverting items transported by the conveyor inthe first direction to one of a plurality of stations adjacent thediverter that are spaced from one another in the first direction, whenpositioned in a diverter region of the conveyor, in response to a firesignal. The diverter system also includes a source of destinationinformation identifying one of the plurality of stations to which itemstransported by the conveyor are to be diverted, and a controller systemconnected to the diverter and the source for generating, and providingto the diverter, a fire signal for each item transported by the conveyorbased on destination information from the source regarding the one ofthe plurality of stations to which the item is to be diverted.

A second aspect of the invention is a conveyor system including aconveyor having at least one diverter region. In addition, the conveyorsystem includes the diverter system described above, with a diverterbeing arranged in the diverter region of the conveyor.

A third aspect of the invention is a diverter system for diverting itemshaving first and second item tracking points to one of a plurality ofstations, each station having a central axis and a divert axis. Thediverter system is designed for use with a conveyor for transportingitems in a first direction, the conveyor having at least one diverterregion in which the diverter system is positionable. The diverter systemcomprises a diverter for diverting items transported by the conveyor inthe first direction to one of a plurality of stations adjacent thediverter that are spaced from one another in the first direction, whenpositioned in a diverter region of the conveyor, in response to a firesignal. The diverter system also includes a source of destinationinformation identifying one of the plurality of stations to which itemstransported by the conveyor are to be diverted. It also includes an itemmeasuring system for generating information representative of the lengthof items transported by the conveyor and for providing a length signalbased on such information for each item indicating the length of theitem. In addition, the diverter system includes a controller systemconnected to the diverter, the source and the item measuring system, forgenerating a fire signal for each item to be diverted and providing thefire signal to said diverter. The controller system contains informationrepresenting a first length, and the fire signal is generated for eachitem to be diverted based on destination information from the sourceregarding one of the plurality of stations to which the item is to bediverted and as a function of the length signal for such item so thatthe fire signal causes the diverter to divert items that are less thanthe first length substantially when the first item tracking point of theitem arrives at the divert axis for the one of the plurality of stationsand for diverting items that are greater than the first lengthsubstantially when the second item tracking point of the item arrives atthe central axis for the one of the plurality of stations.

A fourth aspect of the invention is a conveyor system including aconveyor having at least one diverter region. In addition, the conveyorsystem includes the diverter system described in the immediatelypreceding paragraph, with a diverter being arranged in the diverterregion of the conveyor.

A fifth aspect of the invention is a method of diverting items movingalong a conveyor having a diverter to one of a plurality of stationsadjacent the diverter. The method comprises, as a first step, providingdestination information for each item transported by the conveyoridentifying the one of the plurality of stations adjacent the diverterto which said each item is to be diverted. The method also includes thestep of diverting said each item from the conveyor to said one of theplurality of stations based on said destination information for saideach item.

A sixth aspect of the invention is a modular conveyor system comprisinga plurality of modular conveyor sections. Each section includes (1) aconveyor for transporting items in a first direction, wherein theconveyor is connectable to conveyors in other ones of the modularconveyor sections so as to form a continuous conveyor assembly, (2) adiverter for diverting items transported by the conveyor in the firstdirection to one of a plurality of stations adjacent the diverter thatare spaced from one another in the first direction in response to a firesignal, and (3) a controller system connected to the at least onediverter for providing a fire signal to the at least one diverter foreach item to be diverted, wherein the controller system is connectableto the controller systems in other ones of the modular conveyor sectionsso as to permit fire signals to be communicated between the controllersystems. The modular conveyor system also includes a source ofdestination information identifying a one of the plurality of stationsin the modular conveyor system to which each item transported by themodular conveyor system is to be diverted. Also, the modular conveyorsystem has a host controller connected to the source and to thecontroller systems, wherein the host controller generates the firesignal for each item transported by the modular conveyor system based onthe destination information from the source, and provides the firesignal to at least one of the controller systems.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, the drawings show a formof the invention that is presently preferred. However, it should beunderstood that the present invention is not limited to the precisearrangements and instrumentalities shown in the drawings, wherein:

FIG. 1 is a schematic plan view of a conveyer system according to thepresent invention;

FIG. 2 is a schematic diagram of the controller unit for the conveyorsystem of FIG. 1;

FIG. 3 is a flow diagram setting forth the initial steps for controllingthe operation of the conveyor system of FIG. 1;

FIG. 4 is a flow diagram setting forth the steps for determining thelength of an item conveyed by the conveyor system of FIG. 1, and theposition of its leading edge, trailing edge and mid-point;

FIG. 5 is a flow diagram setting forth the steps for implementing themulti-fire mode of operation with the conveyor system illustrated inFIG. 1;

FIG. 6 is a flow diagram setting forth the steps for implementing thevariable fire mode of operation with the conveyor system illustrated inFIG. 1;

FIG. 7 is a schematic diagram of the conveyor system illustrating thediversion of an item in accordance with the variable fire mode ofoperation;

FIG. 8 is a flow diagram setting forth the steps for performing theenhanced diverting method according to the present invention, whichinvolves both variable fire and multi-fire modes; and

FIG. 9 is a schematic diagram of a conveyor system of the presentinvention comprising multiple conveyor sections.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to conveyor systems and conveying methodsand, in particular, to such systems and methods having a multi-fire modeof operation involving multiple diversion points on a single diverter, avariable fire mode of operation involving a variable diversion point ona single diverter and a combination of both.

With reference to FIG. 1, a first aspect of the invention is a conveyersystem 10 comprising a frame 12 which supports a plurality of parallelconveyor belts 14 that move from left to right over the frame at a speeddetermined by a conveyor belt drive controller 15 operatively connectedto the conveyor belts. System 10 further includes one or more diverterregions DR with a front edge DRF, a back edge DRB and a center DRC, inwhich is located a diverter 16 for diverting items 18, such as items 18a-18 e, from the direction of travel of conveyor belts 14, as indicatedby arrow 17. Diverter 16 includes a plurality of rollers 20 locatedbetween and parallel to belts 14. Rollers 20 are preferably disposedbelow the level of belts 14 and are capable of being raised to the levelof belts 14 or slightly above, so as to engage one or more of items 18a-18 e when one or more of the items needs to be diverted from conveyor10, as described in more detail below. A suitable diverter 16 isdisclosed in U.S. Pat. No. 6,085,892.

System 10 also includes a photodetector system PD arranged upstream ofdiverter 16 at or near an input end 34 of conveyor system 10 at apredetermined distance film diverter region DR. Photodetector system PDcomprises a photodetector 30 on one side of frame 12 and a “tick”generator 32, shown located on the opposite side of the frame.Photodetector 30 may be, for example, a diffuse photoeye. Tick generator32 is in electrical communication with controller 15 and controller unit40 (discussed below) and generates ticks corresponding to the speed ofconveyor belts 14. Tick generator 32 may include, for example, a lightsource and a detector with a beam chopper disposed therebetween, withthe beam chopper driven in proportion to the speed of conveyor belts 14.An exemplary tick generator 32 is made by Telemechanique (a division ofSquare D), model no. XUB-JO83135D. An exemplary photodetector 30 is atransmissive opto schmitt sensor made by Honeywell, model no.HOA0973-N55.

Tick generator 32 emits ticks, the timing of which is related to thespeed of conveyor belts 14. Thus, each tick interval P corresponds to adistance of travel x of conveyor belts 14, e.g., one tick for each inchof travel, and hence the distance of travel of an item carried thereon.Thus, for n ticks, the distance of travel of an item down the conveyoris nx.

System 10 further includes a controller unit 40 in electricalcommunication with photodetector system PD, conveyer belt drive unit 15,diverter 16 and tick generator 32. A suitable controller unit 40 for thepresent invention may be the controller described in U.S. Pat. Nos.6,085,892 and 5,984,498. Controller unit 40 controls the functions andoperation of conveyor apparatus 10 of the present invention, includingdiverter 16, as described in more detail below.

System 10 also includes destination information source 46, which is inelectrical communication with control unit 40. Destination informationsource 46 contains information regarding which diverter 16 in system 10will be used to divert a given item 18 and, optionally, which station 50and 52 (described below) adjacent the diverter will receive the item.Destination information source 46 may comprise a conventional bar codereader system for detecting and decoding information contained in a barcode (not shown) applied to an item 18. Suitable known bar code readersystems are described in U.S. Pat. Nos. 5,323,878, 5,412,196 and5,412,197, which are incorporated herein by reference. Bar codes appliedto items 18 may contain a unique identification code for the item, itsfinal destination (e.g., shipping address of the party receiving theitem), the diverter 16 to be used to divert the item and, optionally,the station 50 or 52 within a given diverter to which the item is to bediverted.

Alternatively, destination information source 46 may include computermemory (not shown) for storing a sequence table that assigns adestination based on the order of arrival of items at photodetectorsystem PD. For example, if there is a conveyor system, such as multipleconveyor system 400 described below, where there are n diverters 16 a,16 b . . . 16 n, the sequence table could be configured to send a firstitem to diverter 16 a, a second item to diverter 16 b, a third item todiverter 16 c, a fourth item to diverter 16 a, a fifth item to diverter16 b, etc. Alternatively, the sequence table could also be configured tosend the first three items to diverter 16 a, the next three to diverter16 c, the next three to diverter 16 c, the next three to diverter 16 a,etc. In any event, destination information source 46 preferablycomprises a lookup table that contains the above-described destinationinformation for each item 18 being conveyed, or that will be conveyed,by system 10.

Located adjacent conveyor system 10 on either side of diverter 16 are aplurality of stations 50 and 52, illustrated in FIG. 1 as includingstations 50-1, 50-2, 50-3 and 52-1, 52-2, 52-3, respectively, arrangedalong the direction of travel on either side of the conveyor system, forreceiving one or more items 18 a-18 e that are diverted from theconveyor system. Stations 50 and 52 may comprise, for example, astacker, one or more bins, a conveyor or other known devices forreceiving an item 18. While stations 50 and 52 have been illustrated inFIG. 1 to each have three stations, it is to be appreciated greater andlesser numbers of stations may be used.

With reference now to FIG. 2, controller unit 40 is now described inmore detail. Controller unit 40 comprises a processor 60, a read-writememory 61, status lights 62, a signal generator 63, a battery 64,input/output (I/O) port 66 and an amplifier 67. Also included is atleast one inflow bi-directional communications port 68 (68 a, 68 b) andcorresponding outflow bi-directional communications port 70 (70 a, 70b). The bi-directional communication ports 68 and 70 are preferablyRS485 connectors with two RJ31X modular connections. Below is describedin detail a conveyor system 400 made up of a plurality of conveyorsystems 10. In this conveyor system 400, individual controller units 40are interconnected to each other for bi-directional communicationtherebetween.

Controller unit 40 is powered in any of a number of ways. In oneembodiment, electrical power is supplied to the controller via a cableinterconnecting communication ports 68 and 70 of each controller unit.Thus, each controller unit 40 may be powered from a central source. Thecentral power supply provides power in the range of from about 20 Vac toabout 52 Vac and preferably is about 24 Vac or about 48 Vac.Alternatively, each controller unit 40 or a group of such controllerunits is connected to a power supply in the above voltage ranges.

Battery 64 is preferably a 3V Lithium coin cell or any long-life typebattery known in the art. Battery 64 supplies backup power to read/writememory 61 in the event of a power failure, so that data is retaineduntil power is restored. For a conveying or sorting system application,the information retained includes item tracking information andconfiguration parameters for conveyor system 10. Also included isinformation concerning items 18 traversing the section of conveyorsystem 10 under the control of the controller unit 40, and any sortingor routing instructions for these items. Alternatively, or in additionto battery 64, controller 40 may use non-volatile memory of the typethat retains information when there is a power failure.

Additionally, one or more external input devices 74 can be disposedalong conveyor system 10 to sense the item being diverted or sorted. Inthis way, processor 60 can determine if a proper diversion was made orwhether conveyor system 10 performed an incorrect diverting operation.

Processor 60 can thus evaluate these and other inputs to determine ifconveyor system 10 is in a failed or faulted condition, and can providean output indicating this failed condition to prevent further operationor action by the failed/faulted conveyor system.

Processor 60 preferably includes a non-volatile random access memory(NVRAM) 76, an EEPROM 78, and a central processing unit (CPU) 80. Theapplications program or software routines for operating conveyor system10 are preferably stored in EEPROM 78, which is easily removed in thefield for replacement. The configuration parameters preferably arestored in NVRAM 76 so they are easily changed in the field, particularlyby the user.

NVRAM 76 stores data and any parameters required for the operationand/or configuration of each controller unit 40. For example, the dataregarding items in an area or section under the control of a givencontroller unit 40, and any related tracking and routing data for eachof these items is stored in the NVRAM. Further, the configurationparameters required to enable the control routines for a given sectiontype of a conveying system are also stored therein.

A suitable CPU 80 is a PIC17C43 by MicroChip Corp., and alternativelymay be PIC17C44 by MicroChip Corp. The software routines stored inEEPROM 78 are loaded into CPU 80 and specific routines are enabled bymeans of the configuration parameters retrieved from NVRAM 76.

With reference to FIGS. 1-3, the operation of conveyor system 10according to a first aspect of the present invention is now described.The operation steps described below are implemented via a softwareprogram preferably stored in EEPROM 78 which is executed by CPU 80 incombination with NVRAM 76. As those skilled in the art will appreciate,the operational steps described below may be implemented with one of avariety of programming languages. In the first step 102, one of items 18a-18 e is placed onto the conveyor belts 14 at input end 34. Next, instep 104, photodetector system PD detects the presence of item 18 as itpasses therethrough. Based on information provided by photodetectorsystem PD, controller unit 40 determines the length L_(I) of item 18 inthe direction of travel of conveyor belts 14, represented by arrow 17,and the relative positions of the item's leading edge 18 _(L), trailingedge 18 _(T), and/or mid-point MP (see item 18 a in FIG. 1).

Referring now to also to FIG. 4, step 104 itself includes a number ofsteps 104 a-104 e pertaining to how the length L_(I) of items 18 and theitem's leading edge 18 _(L), trailing edge 18 ^(T), and/or in mid-pointMP are determined. The position of item 18 relative to a point onconveyor system 10 (e.g., input end 34) is continuously updated as theitem travels down the conveyor system, as described below.

In step 104 a, as item 18 passes photodetector PD a light signal isreflected from the item and received by the photodetector 30, causingthe signal to go high for N ticks (alternatively, the signal could golow). Next, in step 104 b, photodetector 30 transmits an electricalsignal to controller unit 40 indicating the presence of item 18, i.e., ahigh signal, while tick generator 32 continuously transmits a pulsetrain of ticks to controller 40. Then, in step 104 c, based on thesignals transmitted in step 104 b, controller unit 40 calculates thelength L_(I) of the item 18 along its direction of travel by multiplyingthe number of ticks, during the time the output of photodetector 30indicates the presence of an item, by the distance of travel per tick x,i.e., L_(I)=Nx. For example, controller unit 40 may be programmed tointerpret one tick as equivalent to one inch of travel, plus or minusten percent. The actual conversion factor may vary because of mechanicaltolerance build-up. In practice, the conversion factor may be measuredvia observation after the conveyor system is assembled.

Also, it will be apparent to one skilled in the art that either atime-based or distance-based calculation may be used in implementing thepresent invention. It may be preferable in some instances to use adistance-based calculation, because the conveyor belts 14 could stop forperiods of time. In this case, tick generator 32 would stop generatingticks. On the other hand, the time-based calculation can be suspendedwhen there is no movement of items 18 down conveyor system 10.Accordingly, the present invention is not limited to either a time-basedor a distance-based calculation in its implementation.

Next, in step 104 d, controller unit 40 also calculates the position ofleading edge 18 ^(L), trailing edge 18 _(T), and/or mid-point MP of item18, as selected, passing through photodetector system PD relative to thephotodetector system. This is accomplished by noting the arrival of theleading edge 18 _(L) and counting the number of ticks until trailingedge 18 _(T) or mid-point MP of the item passes through photodetectorsystem PD. This number is N, as discussed above. The distance theleading edge 18 _(L) of item 18 has traveled down conveyor system 10 isequal to the length L_(I)=Nx when the moment the leading edge of theitem passes photodetector system PD. The position of the leading edgeand trailing edge of item 18 is continuously updated as the item travelsdown conveyor system 10 at a fixed rate of speed s. Thus, tick generator32 (or signal generator 63) provides a signal at an interval t that isused in calculating the distance an item 18 travels. Controller unit 40determines the distance X an item 18 has traveled at any instant bycounting the number of ticks emitted from tick generator 32, so thatX=s(nt). Controller unit 40 maintains an array of data records for eachitem 18 under its control. These records correlate an item 18identification with the item's position. Further, controller unit 40 isprogrammed with the number of ticks between a reference point onconveyor system 10 and various points along the direction of travel ofan item, such as back edge DR_(B), front edge DR_(F), or pointstherebetween.

Finally, in step 104 e, the position X_(MP) of the mid-point of item 18is calculated and tracked as the item travels down the conveyor.Position X_(MP) of the mid-point is simply half-way between the leadingand trailing edge locations of item 18, as ascertained above. If theleading and trailing edge positions as a function often relative to areference point on conveyor system 10 are X_(LE)(t) and X_(TE)(t),respectively, then the location of the item's mid-point as a function oftime is X_(TE)(t)+L_(I)/2 or X_(LE)(t)−L_(I)/2. If the variable firefunctionality of conveyor system 10, described below, is not used, step104 e may be omitted.

With reference again to FIG. 3, at step 106, destination information isacquired by control unit 40 for an item 18 from destination informationsource 46. As noted above, this information includes the diverter 16 tobe used to divert the item and, optionally, the station 50 or 52 towhich the item is to be diverted.

Multi-fire Mode

With continuing reference to FIG. 3 and flow diagram 100, at query step110, a determination is made whether system 10 is to be operated in amulti-fire mode, a variable fire mode or both. The multi-fire mode isused when it is desired to divert items 18 to different stations withinstations 50 or 52 in a given diverter 16, such as stations 50-1 to 50-3and/or stations 52-1 to 52-3. The multi-fire mode of operation providesgreatest benefit when length L_(I) of items 18 is significantly lessthat the length L_(D) of diverter 16.

The multi-fire mode of operation is described with reference again toFIG. 1 and also to flow diagram 120 of FIG. 5, which is a continuationof flow diagram 100 of FIG. 3. In step 122, a station and stationdestination is retrieved for the item (e.g., item 18 d to station 50-1)based on information contained in destination information source 46.This information is provided to controller unit 40. Controller unit 40also includes information pertaining to the distance from input end 34of conveyor system 10 (or any other fixed location on the conveyorsystem) to positions along the length of each diverter 16 (in thedirection of arrow 17) where a corresponding respective station 50 or 52is located. This information may be in the form of the number of ticks,which represent a given distance as discussed above.

Next, at step 124, controller unit 40 calculates the amount of time ordistance (number of ticks) it takes either the leading edge 18 _(L),mid-point MP, trailing edge 18 _(T) or other point (such points arehereinafter referred to generally as item tracking point 125, e.g.,trailing edge 18 _(T) of item 18 a) after passing through photodetectorsystem PD to reach alignment with the selected station 50 or 52 to whichthe item 18 is to be diverted. This calculation may be made bycontroller unit 40 in absolute time units or in terms of distance basedon the number of ticks emitted by tick generator 32 during the periodwhen item tracking point 125 of item 18 travels from a given referencepoint, e.g., leading edge 34, on conveyor system 10 to the position indiverter 16 adjacent a selected station 50 or 52. Controller unit 40then generates a diverter fire signal based on this calculation which isprovided to diverter 16. This diverter fire signal contains informationthat directs diverter 16 when to fire.

In practice, calculation of a diverter fire signal may simply consist ofcontroller unit 40 referencing predetermined distances or ticks betweenstations 50 and 52 stored in destination information source 46 or EEPROM78. For example, a diverter 16 may be spaced the distance represented by300 ticks provided by tick generator 32 from leading edge 34 of conveyorsystem 10. Each station 50 or 52 may be spaced from adjacent stations bythe distance represented by 12 ticks. Controller unit 40 counts downsuch tick amount beginning when an item tracking point passes areference point on conveyor system 10, e.g., photodetector 30 or astation 50 or 52. When such tick count is completed this defines whenthe item tracking point has arrived at a location where it is intendeddiverter 16 should fire. At such location, controller unit 40 queriesdestination information Source 46 to assess if controller unit 40 shouldprovide a diverter fire signal to diverter 16. If so, a fire signal isprovided. If not, a new tick count is retrieved and a new tick countdowncommences.

In step 126, pursuant to information in the diverter fire signalprovided by controller unit 40, the diverter fires. This diverts theitem 18 into its assigned station 50 or 52. This firing step involvesdiverter 16 operating, e.g., by initiating rotation of rollers 20 in theappropriate direction, and raising the rollers above the level of belts14, so as to divert the item 18. For example, in FIG. 1, item 18 d isshown being diverted into its assigned station 50-1 on one side of theconveyor, and item 18 e is shown being diverted into its assignedstation 52-3 on the other side of the conveyor at a location downstreamfrom station 50-1.

Variable Fire Mode

With reference again to FIG. 3 and flow diagram 100, if at query step110 the variable fire mode is selected, then the operation of conveyorsystem 10 is controlled in accordance with flow diagram 140 illustratedin FIG. 6. The variable fire mode of operation involves diverting anitem 18 from conveyor system 10 when item tracking point 125 reaches aselected position along the length of diverter 16 as a function of theitem length L_(I).

Accordingly, with reference to FIGS. 1, 3, 6 and 7, to facilitatedescription of the variable fire mode of operation there is shown aconveyor system 130 which is identical to conveyor system 10 of FIG. 1,described above, except that stations 50 and 52 have been replaced witha station 137 having a central axis A, the station being arrangedadjacent frame 12 next to diverter region DR.

Assuming the query at step 110 results in selection of the variable fireoption, operation of conveyor system 10 proceeds in accordance with thesteps of flow diagram 140. At step 141, a determination is made whetherlength L_(I) of item 18 is greater than a predetermined reference lengthL_(R). The latter may be equal to the length L_(D) of diverter regionD_(R), or may be of greater or lesser length, as those of ordinary skillin the art may readily determine by routine testing. If item 18, e.g.,item 18′ in FIG. 7, has a length L_(I) greater than L_(R), then in step142 controller unit 40 sets a selected item tracking point 125 as thepoint of item 18′ to be aligned with central axis A when the diverter 18is fired. In the immediately following discussion item tracking point125 is assumed to be mid-point MP, for the sake of simplicity.

Next, in step 144, based on the speed of travel of item 18, controllerunit 40 calculates the distance to be traveled (in ticks), or time ittakes, for mid-point MP of item 18, determined at step 104, to alignwith central axis A of station 137. Central axis A is at or near themid-point of diverter 16, as measured in the direction of arrow 17.Based on this determination, controller unit 40 generates a diverterfire signal provided to diverter 16 in response to this timinginformation. More specifically, the timing of the diverter fire signalmay be calculated by determining the number of ticks generated by tickgenerator 32 it takes for item mid-point MP to travel to central axis A.In step 146, when such alignment occurs, diverter 16 fires, therebydiverting item 18 to station 137. This allows a large package to bediverted to a station 137 without being twisted or spun.

While it is often preferred to fire diverter 16 when an item 18 having alength L_(I) that is >L_(R) is positioned so that its mid-point MP isaligned with central axis A, the present invention is not so limited. Atstep 142, the item tracking point 125 may be set at any point betweenleading edge 18 _(L) and trailing edge 18 _(T) of item 18′. This isaccomplished by controller unit 40 performing a calculation, inaccordance with user input, that sets the item tracking point 125 at anyselected location between leading edge 18 _(L) and trailing edge 81_(T). For example, to establish an item tracking point 125 that isdirectly in between leading edge 18 _(L) and mid-point MP, controllerunit 40 takes the average of the position of leading edge 18 _(L) andmid-point MP.

In the next step 144, controller unit 40 calculates the distance to betraveled (in ticks) or time for the selected item tracking point 125 toalign with the station central axis A. In step 146, when such alignmentoccurs, diverter 16 fires in response to a fire signal generated bycontroller unit 40, thereby diverting item 18′ to station 137.

With continuing reference to FIG. 6, if at step 141 it is determinedthat item 18 has a length L_(I) that is not >L_(R), then operation ofconveyor system 130 proceeds to step 152. There, item tracking point 125is set, preferably at or near leading edge 18 _(L). Next, at step 154,controller unit 40 calculates the distance to be traveled (in ticks) orthe time required for the item tracking point 125 to align with divertaxis B, as described above in connection with the description of suchtime calculation with respect to central axis A. Typically, but notnecessarily, divert axis B is not coincident with central axis A, and isusually positioned closer to back edge DR_(B) of diverter 16 thancentral axis A. The exact position of divert axis B will vary as afunction of the speed of conveyor system 130, the weight and size ofitem 18″ and other factors, and may be readily determined by those ofordinary skill in the art through routine experimentation. Finally, atstep 156, diverter 16 is fired in accordance with a fire signal receivedfrom controller unit 40, which such un it generates based on thedistance or time calculation described above.

The concept of variable diversion is of particular importance forhigh-speed conveyors. For example, when a relatively small item 18, suchas item 18′, travels on a high-speed conveyor, it acquires a momentumP=mv, where m is the mass of the package and v is its velocity. Becauseof this momentum, item 18 may follow a curved path when it is divertedfrom the conveyor system 10 or 130. Accordingly, it is necessary to firediverter 16 so that the curved path along which item 18 travels whendiverted results in the items being appropriately positioned on station137.

Enhanced Diverting Method

The multi-fire and variable modes of operation were described above asseparate operations to facilitate description of the invention. However,these two methods are combinable in a single enhanced diverting method.With reference again to FIGS. 1-3 and 8, if at step 110 (FIG. 3) adetermination is made to select both multi-fire and variable fire modesof operation, then the operation of controller system 10 proceeds inaccordance with the steps of flow diagram 300. The steps of flow diagram300 comprise a combination of various steps of the flow diagrams earlierdescribed.

First, in step 302, the item length L_(I) is determined, as describedabove in connection with step 104. Next, in query step 304, the itemlength L_(I) is compared to reference length L_(R), as described abovein connection with step 141. For example, the latter may be set to besubstantially equal to length L_(D)) of diverter 16, to L_(D)/2 or toanother value. If the item length L_(I) is longer than reference lengthL_(R), then the method proceeds to step 306, where item tracking point125 is set at a selected point on item 18 between its leading edge 18_(L) and trailing edge 18 _(T), often adjacent mid-point MP, asdescribed above in connection with step 142. If at step 304 item lengthL₁ is not >L_(R), then the process continues to step 308. There, itemtracking point 125 is set, typically proximate leading edge 18 _(L), asdescribed above in connection with step 152. After both steps 306 and308, the process proceeds to step 310 where one of stations 50 and 52and associated stations on diverter 16 is retrieved, as described abovein connection with step 122. Then, at step 312, the distance to betraveled or amount of time required for the selected item tracking point125 to become aligned with the assigned station 50 or 52 is calculated,as described above in connection with step 124. Finally, at step 312,diverter 16 fires when the selected item tracking point 125 is aligned,pursuant to a diverter fire signal provided by controller unit 40.

Multiple Conveyor System

With reference now to FIG. 9, a conveyer system 400 according to asecond aspect of the invention is now described. Conveyor system 400includes n conveyer sections 10 a, 10 b, . . . 10 n arranged in series,with each equivalent to a single conveyor system 10, described above.Each section 10 a, 10 b, . . . 10 n also includes a photodetector systemPDa, PDb, . . . PDn, respectively, and a diverter 16 a, 16 b, . . . 16n, respectively, and controller units 40 a, 40 b, . . . 40 n,respectively. In conveyor sections 10 a-10 n, destination informationsource 46 is not required, but is included in conveyor system 400, asdiscussed below. In addition, controller units 40 a, 40 b, . . . 40 nare connected to form what is effectively a single controller unit 410for system 400. Controller units 40 a, 40 b, . . . 40 n are inelectrical communication with a host controller 412. Associated withsections 10 a, 10 b, . . . 10 n are stations 50 a, 50 b, . . . 50 n, andstations 52 a, 52 b, . . . 52 m, respectively. Thus, conveyor system 400is a modular conveyor system.

During set-up of conveyor system 400, the relative distances betweendiverters 16 a, 16 b, . . . 16 n is programmed into each controller unit40 a, 40 b, . . . 40 n. This information is generated by determining thedistance from the beginning of a conveyor section, e.g., 10 a, to thelocation of a diverter 16 a, 16 b, . . . 16 n, and the distance betweenconveyor sections. The distance between diverter 16 a, 16 b, . . . 16 nis used to time the firing of the diverters. This distance may berepresented in the form, the number of ticks, or timing signalsgenerated by signal generator 63 in host controller 412. In any event, asignal representative of distance between diverters is sent to allcontroller units 40 a, 40 b, . . . 40 n so that a universal reference isestablished.

For a more detailed description of conveyor system 400, attention isdirected to U.S. Pat. Nos. 6,085,892 and 5,984,498, which contain adescription of suitable modular conveyor controller systems.

In operation, an item 18 enters conveyor section 10 a at input and 34.As described above, as item 404 passes photodetector system PDa, it isassigned a station to which it is to be diverted from informationobtained by host controller 412 from destination information source 46in electrical communication therewith. This diversion might involve themulti-fire mode of operation, the variable fire mode of operation, orboth. This information is passed from host controller 412 to firstcontrol unit 40 a. If item 18 is to be diverted to, for example, tostation 52 n, then item 18 needs to be conveyed from section 10 a tosection 10 n without being diverted. To accomplish this, controller unit40 a passes the diverting information pertaining to item 18 tocontroller unit 40 b, which in turn passes this information to the nextcontroller unit, until the information reaches controller unit 40 n. Inother words, the responsibility for diverting item 18 is transferred indaisy chain fashion until it reaches the controller unit 40 n for thesection 10 n in which the item 18 is to be diverted.

Controller units 40 a-40 n are preferably interconnected to each otherfor communication by appropriately interconnecting the inflow andoutflow bi-directional communications ports 68 and 70 of adjacentcontroller units. Controllers 40 a-40 n are preferably connected to eachother using a “daisy chain” topology, e.g., by interconnecting to anoutflow bi-directional communications port 70 a of controller unit 40 aand into an inflow bi-directional communications port 68 b of secondcontroller unit 40 b. Thus, a bi-directional communications link isestablished between all controller units 40 a to 40 n for thecommunication of data and information therebetween. Such interconnectionand bi-directional communication is also described in more detail inconnection with the controller system described in U.S. Pat. Nos.6,085,892 and 5,984,498.

While the present invention has been described in connection withpreferred embodiments, it will be understood that it is not so limitedto those embodiments. On the contrary, it is intended to cover allalternatives, modifications, and equivalents as may be included withinthe scope of the invention as defined in the appended claims

What is claimed is:
 1. A method of diverting items moving in a directionalong a conveyor having a divercer to any one of a plurality of stationsadjacent the diverter and spaced from one another along the direction ofthe conveyor, comprising the steps of: providing destination informationfor each item transported by the conveyor identifying the one of theplurality of stations adjacent the diverter to which said each item isto be diverted; and diverting said each item with the diverter from theconveyor to any one of said one of the plurality of stations based onsild destination information for said each item.
 2. A method accordingto claim 1, wherein said each item to be diverted has an item trackingpoint, further wherein said diverting step involves diverting said eachitem when said item tracking point is positioned in a first relationshipto said one of said plurality of stations.
 3. A method according toclaim 1, further wherein said diverting step involves diverting saideach item based on the length of said item.
 4. A diverter system fordiverting items to one of a plurality of stations, the diverter systemdesigned for use with a conveyor for transporting items in a firstdirection, the conveyor having at least one diverter region in which thediverter system is positionable, the diverter system comprising: adiverter for diverting systems items transported by the conveyor in thefirst direction to any one of a plurality of stations adjacent saiddiverter that are spaced from one another in the first direction, whenpositioned in a diverter region of the conveyor, in response to a firesignal; a source of destination information identifying one of theplurality of stations to which items transported by the convey or are tobe diverted; and a controller system connected to said diverter and saidsource for generating, and providing to said diverter, a fire signal foreach item to be diverted based on destination information from saidsource regarding one of the plurality of stations to which said item isto be diverted.
 5. A diverter system according to claim 4, wherein saidcontroller system tracks the location of items transported on theconveyor and generates said fire signal based on both said destinationinformation and the location of an item to be diverted on the conveyor.6. A diverter system according to claim 5, each item having an itemtracking point, wherein said controller system includes a detector fordetecting when items pass a first location on the conveyor and saidcontroller system generates said fire signal when the item trackingpoint of an item to be diverted is a first distance from said detector.7. A diverter system according to claim 6, wherein said first distanceis selected so that the item to be diverted is proximate the one of theplurality stations to which the item is to be diverted.
 8. A divertersystem according to claim 5, wherein said controller provides said firesignal to said diverter when the item to be diverted is proximate theone of the plurality stations to which the item is to be diverted.
 9. Aconveyor system for transporting items in a first direction anddiverting the items to one of a plurality of stations, the systemcomprising: a conveyor having at least one diverter region; a pluralityof stations adjacent said at least one diverter region that are spacedfrom one another in the first direction; at least one diverter, arrangedin said at least one diverter region, for diverting each itemtransported by said conveyor in the first direction to any one of saidplurality of stations in response to a fire signal; a source ofdestination information identifying one of said plurality of stations towhich each item transported by the conveyor is to be diverted; and acontroller system connected to said at least one diverter and source forgenerating, and providing to said at least one diverter, a fire signalfor each item to be diverted based on destination information from saidsource.
 10. A conveyor system according to claim 9, wherein saidcontroller system tracks the location of items transported on theconveyor and generates said fire signal based on both said destinationinformation and the location of an item to be diverted on the conveyor.11. A conveyor system according to claim 10, each item having an itemtracking point, wherein said controller system includes a detector fordetecting when items pass a first location on the conveyor and saidcontroller system generates said fire signal when the item trackingpoint of an item to be diverted is a first distance from said detector.12. A conveyor system according to claim 11, wherein said first distanceis selected so that the item to be diverted is proximate the one of theplurality stations to which the item is to be diverted.
 13. A divertersystem according to claim 10, wherein said controller provides said firesignal to said diverter where the item to be diverted is proximate theone of the plurality stations to which the item is to be diverted.
 14. Adiverter system for diverting items having first and second itemtracking points to one of a plurality of stations, each station having acentral axis and a divert axis, the diverter system designed for usewith a conveyor for transporting items in a first direction, theconveyor having at least one diverter region in which the divertersystem is positionable, the diverter system comprising: a diverter fordiverting items transported by the conveyor in the first direction toany one of a plurality of stations adjacent said diverter that arespaced from one another in the first direction, when positioned in adiverter region of the conveyor, in response to a fire signal; a sourceof destination information identifying one of the plurality of stationsto which items transported by the conveyor are to be diverted; an itemmeasuring system for generating information representative of the lengthof items transported by the conveyor and for providing a length signalbased on said information for each item indicating the length of theitem; and a controller system connected to said diverter, said sourceand said item measuring system, for generating a fire signal for eachitem to be diverted and providing said fire signal to said diverter,wherein said controller system contains information representing a firstlength, further wherein said fire signal is generated for each item tobe diverted based on destination information from said source regardingone of the plurality of stations to which said item is to be divertedand as a function of said length signal for said item so that said firesignal causes said diverter to divert items that are less than saidfirst length substantially when the first item tracking point of theitem arrives at said divert axis for said one of said plurality ofstations and for diverting items that are greatar than said first lengthsubstantially when the second item tracking point of the item arrives atsaid central axis for said one of said plurality of stations.
 15. Adiverter system according to claim 14, wherein said controller systemtracks the location of items transported on the conveyor and generatessaid fire signal based on both said destination information and thelocation of an item to be diverted on the conveyor.
 16. A conveyorsystem for transporting items in a first direction, the items having afirst item tracking point and a second item tracking point, the systemcomprising: a conveyor having at least one diverter region; a pluralityof stations adjacent said at least one diverter region that are spacedfrom one another in the first direction; a diverter for diverting itemstransported by the conveyor in the first direction to any one of saidplurality of stations adjacent said diverter in response to a firesignal; a source of destination information identifying one of theplurality of stations to which items transported by the conveyor are tobe diverted; an item measuring system for generating informationrepresentative of the length of items transported by the conveyor andfor providing a length signal based on said information for each itemindicating the length of the item; and a controller system connected tosaid diverter, said source and said item measuring system, forgenerating a fire signal for each item to be diverted and providing saidfire signal to said diverter, wherein said controller system containsinformation representing a first length, further wherein said firesignal is generated for each item to be diverted based on destinationinformation from said source regarding one of the plurality of stationsto which said item is to be diverted and as a function of said lengthsignal for said item so that said fire signal causes said diverter todivert items that are less than said first length substantially when thefirst item tracking point of the item arrive at said divert axis forsaid one of said plurality of stations and for diverting items that aregreater than said first length substantially when the second itemtracking point of the item arrives at said central axis for said one ofsaid plurality of stations.
 17. A conveyor system according to claim 16,wherein said controller system tracks the location of items transportedon said conveyor and generates said fire signal based on both saiddestination information and the location of an item to be diverted onthe conveyor.
 18. A modular conveyor system, comprising: a plurality ofmodular conveyor sections, each section including: a conveyor fortransporting items in a first direction, wherein said conveyor isconnectable to conveyors in other ones of said modular conveyor sectionsso as to form a continuous conveyor assembly; a diverter for divertingitems transported by said conveyor in the first direction to any one ofa plurality of stations adjacent said diverter that are spaced from oneanother in said first direction in response to a fire signal; and acontroller system connected to said at least one diverter for providinga fire signal to said at least one diverter for each item to bediverted, wherein said controller system is connectable to saidcontroller systems in other ones of said modular conveyor sections so asto permit fire signals to be communicated between said controllersystems; a source of destination information identifying a one of saidplurality of stations in the modular conveyor system to which each itemtransported by the modular conveyor system is to be diverted; and a hostcontroller connected to said source and to said controller systems,wherein said host controller generates said fire signal for each itemtransported by the modular conveyor system based on said destination ainformation from said source, and provides said fire signal to at leastone of said controller systems.
 19. A modular conveyor system accordingto claim 18, wherein: each of said plurality of stations has a centralaxis and a divert axis; the modular conveyor system further includes anitem measuring system fix generating information representative of thelength of items transported by said conveyors in the modular conveyorsystem and for providing a length signal based on said information foreach item indicating the length of the item to said host controller; andwherein said host controller contains information representing a firstlength, further wherein said host controller generates said fire signalfor each item to be diverted based on said destination information fromsaid source regarding one of the plurality of stations to which saiditem is to be diverted and as a function of said length signal for saiditem so that said fire signal causes a respective one of said divertersto divert items that are less than said first length substantially whena first item tracking point of the item arrives at said divert axis forsaid one of said plurality of stations and for diverting items that aregreater than said first length substantially when a second item trackingpoint of the item arrives at said central axis for said one of saidplurality of stations.